Restyle to a clean, flat look and rename brand to SCOPENET

- Brand is now SCOPENET everywhere (defaults, UI, installer, docs)
- Launcher: solid backgrounds (no animated orbs/grain), flat Play button
  without gradient/shine/glow, quieter rail with a simple active
  indicator, smaller type scale, Inter as default font, glass off by
  default, restyled sliders
- Panel: same flat treatment; live preview mirrors the new launcher
- New flat scope-reticle logo and app icons
- Calmer default palette
- Fix: lock the shared cargo cache in the Docker build (amd64/arm64 raced)
- Fix: Windows-only clippy lint in sys.rs

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011ARcGWxLx21FwXJ3yfGriS

crates/core/src/sys.rs

@@ -11,7 +11,7 @@ fn imp() -> Option<u64> {
     let mut status: MEMORYSTATUSEX = unsafe { std::mem::zeroed() };
     status.dwLength = std::mem::size_of::<MEMORYSTATUSEX>() as u32;
     let ok = unsafe { GlobalMemoryStatusEx(&mut status) };
-    (ok != 0).then(|| status.ullTotalPhys / 1024 / 1024)
+    (ok != 0).then_some(status.ullTotalPhys / 1024 / 1024)
 }
 
 #[cfg(target_os = "linux")]